1. Field of the Invention
This invention is concerned with the control of obesity by the introduction of certain fat imbibing polymers into the gastrointestinal tract.
2. Description of the Prior Art
Various polymers have been administered to animals to affect lipid (cholesterol) levels in the blood and liver. Many natural polymers, such as vegetable gums have been administered orally to reduce cholesterol levels. These materials have been reported to act by mechanisms such as increased degradation of cholesterol to bile salts, increased catabolism of cholesterol, and increased excretion of bile acids in fecal material, U.S. Pat. No. 4,175,124.
Synthetic polymers reported as lowering cholesterol levels include the quaternary ammonium styrene-divinylbenzene ion exchange resin, cholestyramine, U.S. Pat. Nos. 3,499,960 and 3,974,272;
a polymerized unsaturated carboxylic acid or anhydride or copolymer thereof with an unsaturated monomer. See, U.S. Pat. Nos. 3,923,972 (U.S. Pat. No. Re. 29,652) and 4,115,550, reporting increased excretion of cholesterol and fat, and diarrhea with severe weight loss in some cases, and weight control via inhibition of pancreatic lipase with certain cationic polymers of this group, in U.S. Pat. No. 4,211,765;
phenylene diamine ion exchange polymers, U.S. Pat. No. 3,980,770;
linear, unbranched, non-crosslinked polyamine resins as binders of bile acids, U.S. Pat. No. 4,027,009;
basic ion exchange resins, U.S. Pat. Nos. 4,041,153 and 4,064,234;
lightly crosslinked, swellable, water-insoluble polyurethanes, Marsh, U.S. Pat. No. 3,953,406, Marsh et al. JPL Quart. Tech. Rev. 2(4) 1-6 (1973), Chem. Abstr. 78:112334 d, and Marsh, JPL Quart. Tech. Rev. 1(1) 49-56 (1971), Chem. Abstr. 75:152435 g;
other crosslinked amine or ammonium polymers, U.S. Pat. Nos. 3,787,474, 3,780,171, 3,692,895.
A number of polymers have been described as useful in separating organic liquids such as fuels, oils, liquid hydrocarbons, by various mechanisms. These include
organic liquid insoluble, organic liquid swellable alkylstyrene, organic-liquid-imbiding polymers, Haigh, U.S. Pat. No. 3,520,806;
non-ionogenic, non-swellable macroreticular adsorbing polymers, Gustafson, U.S. Pat. No. 3,531,463;
lightly crosslinked network polymers for absorbing oil and fat, Fletcher and Marsh, U.S. Pat. No. 4,039,489;
crosslinked urea formaldehyde or melamine formaldehyde resins in highly disperse form, U.S. Pat. No. 3,716,483; and, ion exchange resins, U.S. Pat. No. 3,729,410.
Various methods have been proposed for weight control to combat obesity. One of the more common methods is the use of relatively low-fat diets, i.e., diets containing less fat than a normal diet, although some fat is generally present even in diets considered relatively "fat-free". Fats are solids or liquid oils generally consisting of glycerol esters with higher fatty acids. Dietary sources of fats include both animal and vegetable fats, including predominantly triglyceride esters of both saturated and unsaturated fatty acids, as well as some free fatty acids. Glyceryl tristearate, glyceryl tripalmitate and glyceryl trioleate are among the most common esters.
Maintenance of fat-free or low-fat diets is difficult. The presence of fats in a great many food sources greatly limits the food sources which can be used. Additionally, fats contribute to the flavor, appearance and physical characteristics of many foodstuffs. Such factors adversely affect the acceptability of low-fat diets, and make the maintenance of such diets difficult.
Various chemical approaches have been proposed for controlling obesity. Anorectic agents, such as dextroamphetamine, are associated with undesired side effects. Indigestible materials such as mineral oil or neopentyl esters (see U.S. Pat. No. 2,962,419) have been proposed as substitutes for dietary fat. Diethylaminoethyl dextran, an ion exchange material, has been indicated to inhibit fat absorption in the body. Fischetti, Offenlegungsschrift 2,655,199, Chem. Abstr. 87:112005 h (1977). Garcinia acid and derivatives have been described as treating obesity by interfering with fatty acid synthesis. Swellable crosslinked vinyl pyridine resins have been described as appetite suppressants via the mechanism of providing non-nutritive bulk, U.S. Pat. No. 2,923,662. Cationic polymers such as dialkylaminoimides of alkene/maleic anhydride copolymers have been described as inhibiting pancreatic lipase, U.S. Pat. No. 4,211,765.
None of the above methods have been entirely satisfactory. Controlled diet remains the most prevalent technique for controlling obesity, with surgical techniques such as temporary iliary bypass surgery, being employed in extreme cases. It would be desirable to provide new means for controlling the weight gain producing effects of dietary fat.